Hi John, Thomas,
Can you please review below patch and update your comments:
Regards
Gaurav
On 7/26/2018 2:12 PM, Gaurav Kohli wrote:
While migrating timer to new base, there is a need
to update base clk by calling forward_timer_base to
avoid stale clock , but at the same time if run_timer
is exectuing in new core it may set must_forward_clk
to false and due to this forward base logic may fail as
per below check:
if (likely(!base->must_forward_clk))
return;
So preventing the same by putting must_forward_clk inside
base lock.
Signed-off-by: Gaurav Kohli <gkohli@xxxxxxxxxxxxxx>
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index cc2d23e..675241d 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1657,6 +1657,19 @@ static inline void __run_timers(struct timer_base *base)
raw_spin_lock_irq(&base->lock);
+ /*
+ * must_forward_clk must be cleared before running timers so that any
+ * timer functions that call mod_timer will not try to forward the
+ * base. idle trcking / clock forwarding logic is only used with
+ * BASE_STD timers.
+ *
+ * The deferrable base does not do idle tracking at all, so we do
+ * not forward it. This can result in very large variations in
+ * granularity for deferrable timers, but they can be deferred for
+ * long periods due to idle.
+ */
+ base->must_forward_clk = false;
+
while (time_after_eq(jiffies, base->clk)) {
levels = collect_expired_timers(base, heads);
@@ -1676,19 +1689,6 @@ static __latent_entropy void run_timer_softirq(struct softirq_action *h)
{
struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);
- /*
- * must_forward_clk must be cleared before running timers so that any
- * timer functions that call mod_timer will not try to forward the
- * base. idle trcking / clock forwarding logic is only used with
- * BASE_STD timers.
- *
- * The deferrable base does not do idle tracking at all, so we do
- * not forward it. This can result in very large variations in
- * granularity for deferrable timers, but they can be deferred for
- * long periods due to idle.
- */
- base->must_forward_clk = false;
-
__run_timers(base);
if (IS_ENABLED(CONFIG_NO_HZ_COMMON))
__run_timers(this_cpu_ptr(&timer_bases[BASE_DEF]));
--
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